Time for another short quiz! This one is a little tougher than the last one, I believe. What is the mechanism for the following transformation?


And hey, no looking in SciFinder, Reaxys, Wikipedia, books or the literature. Only pencil, paper and brains are allowed.

The first one to submit the correct answer down below will get a nice prize sent to him or her in the physical world. Go!


10 Responses to What’s the mechanism?

  1. mfomich says:

    nucleophilic ipso-substitution on bromide? (with NH2-)

  2. mfomich says:

    I mean via like-Meisenheimer complex

  3. Hadriel says:

    Looks to me like a nucleophilic acyl substitution, with attack at the Br centre and stabilization of the intermediate by extensive conjugation and charge stabilization due to negative charge landing on electronegative nitrogens. Expulsion of Br should give KBr as a nice solid.

    Just an undergrad’s idea.


  4. Dmitry B says:

    ANRORC obviously, but it’s hard to draw it properly

    • drfreddy says:


      ANRORC is the correct answer indeed. See a thorough explanation with good proofs here.

      Dmitry B, please email me your shipping address so I can send you the prize!

  5. Chymist says:

    May be the substrate can be considered as imidoyl bromide analogue, and accordingly the mechanism would involve addition-elimination sequence, the addition part being facilitated by delocalisation of the negative charge over two N-s
    And, BTW, what does ANRORC stand for?

  6. gfadf says:

    It might have been a bit easier if you’d put the correct reagents? It would have saved us drawing 4+2’s using the Potassium salt of Diimide.

    • drfreddy says:

      wOOt? You never worked with the adduct between potassium hydride and atmospheric nitrogen?

      Seriously, haha… it should be KNH2, of course. I promise to correct the image before the last day of the Maya calendar.

  7. Hap says:

    RORC is ring-opening, ring-closing, I think, and N is nucleophilic, but I don’t remember what A is.

  8. Addition Nucleophilic Ring-Opening Ring-Closing

    Thanks for a fun exercise. A bit anticlimactic after having figured out a good mechanism with KN2H though!

Leave a Reply

Your email address will not be published. Required fields are marked *